Nature
PUBLISHED
While sampling a swamp in Guadeloupe back in 2009, scientists discovered something unusual. About a centimeter long and looking like a pale eyelash, they’d found a bacterium they couldn’t identify. Weirdest of all, it was far bigger than any bacteria ever found before. Far bigger, even, than we thought possible.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.“When I saw them, I thought, ‘strange,’” said Olivier Gros who made the discovery as a marine biology professor at the Université des Antilles in Guadeloupe, in a statement. “In the beginning I thought it was just something curious, some white filaments that needed to be attached to something in the sediment like a leaf.”
At first it was assumed they were eukaryotes because they were too big with too many filaments to be bacteria. A closer look revealed that the identified noodles were some kind of single-celled organism, raising the question as to whether they had found a macro microbe.
Realizing they had something big on their hands – both literally and academically – they began a series of investigations that would support a huge announcement that wouldn’t arrive until 2022: they had found the world’s largest bacteria.
So big are they, in fact, that they're visible to the naked eye. Typically you’d need a microscope to be able to visualize a microbe – the clue is really in the name – but not Thiomargarita magnifica.
“It’s 5,000 times bigger than most bacteria,” said study author Jean-Marie Volland. “To put it into context, it would be like a human encountering another human as tall as Mount Everest.”
Most bacterial cells are microscopic, typically around two micrometers in length. Some "giant bacteria" can be a few hundred micrometers, a size that scientists have previously believed to be the theoretical maximum for the size of a bacterium, but T. magnifica shattered that.
It’s a slightly alarming prospect given humans are covered (inside and out) with microbes. However, it’s not thought to be a pathogen for humans and therefore isn’t going to cause you any problems should you find yourself in a swamp in Guadeloupe.
It forms part of a very interesting habitat, however, as mangroves (along with other kinds of swamps) are celebrated for their impressive carbon sequestration. They contribute to around 10-15 percent of the carbon stored in coastal sediments despite representing less than 1 percent of the coastal area worldwide. Therefore, figuring out what role a giant sulfur-oxidizing, carbon-fixing megabacterium is doing there could have many potential applications.
And if seeing a massive bacterium doesn’t already have you feeling confused, why not listen to the “beautiful and interesting” rumble of one of the world’s largest living organisms?
